NAWMP 2009 Assessment: monitoring and research on diving ducks within the

SFBJV RegionSusan W. De La Cruz and John Y. Takekawa

US Geological Survey, Western Ecological Research Center, San Francisco Bay Estuary Field Station

U.S. Department of the Interior

U.S. Geological Survey

Biological AssumptionsBiological AssumptionsI. Food energy is the primary need of wintering waterfowl

…..adequate foraging habitat will ensure that survival outside ofthe breeding season will not limit population growth

Macroinvertebrate prey Intertidal and subtidal shoals, salt pond foraging habitat

II. Several factors potentially limit access to adequate food and foraging areas:

Habitat modification and loss in foraging areasChanging prey populations Disturbance

III. Contaminants may limit populations independently of adequate food supply; food may be abundant but contaminated

IV. Catastrophic mortality events (i.e. oil spills) are likely given the urban setting and population density

Monitoring of diving ducks in theMonitoring of diving ducks in theSFBJV RegionSFBJV Region

I. Midwinter I. Midwinter 1955 1955 –– 198619861987 1987 –– present (transect based) present (transect based)

II. Monthly surveysII. Monthly surveys1987 1987 –– 1990 Oct 1990 Oct –– Apr, semiApr, semi--monthly, FWS monthly, FWS AccursoAccurso2004 2004 –– 2007 Nov 2007 Nov –– Mar, monthly, USGS WTA StudyMar, monthly, USGS WTA Study

III. Salt pond surveys III. Salt pond surveys 1999 1999 –– present North Baypresent North Bay2002 2002 –– present South Bay present South Bay

IV. Christmas bird count IV. Christmas bird count –– information on sloughs and riversinformation on sloughs and rivers

V. Various area or project based surveysV. Various area or project based surveys

Greater Greater ScaupScaup((AythyaAythya marilamarila))

44% of 44% of scaupscaup counted in lower Pacific Flyway winter in SFBcounted in lower Pacific Flyway winter in SFB

Lesser Lesser ScaupScaup((AythyaAythya affinisaffinis))

0

50000

100000

150000

200000

250000

300000

1955

1959

1963

1967

1971

1975

1979

1983

1987

1991

1995

1999

2003

SFB Scaup combined

Flyway Total Scaup

CanvasbackCanvasback((AythyaAythya valisineriavalisineria))

0250005000075000

100000125000150000175000

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

SFB Canvasback

Flyway TotalCanvasback

Number wintering in the Bay has declined

Migration to Central ValleyChanging prey populations

Surf ScoterSurf Scoter((MelanittaMelanitta perspicillataperspicillata) )

42% of scoters counted in lower Pacific Flyway 42% of scoters counted in lower Pacific Flyway winter in SFBwinter in SFB

020000400006000080000

100000120000140000160000180000200000

1955

1959

1963

1967

1971

1975

1979

1983

1987

1991

1995

1999

2003

SFB Total Scoters (Surf)

Flyway Total Scoters (all spp)

Midwinter Database onlineMidwinter Database online

Access database – queries by species, year, region, transect

Would provide data online for project managers

Recently submitted proposal to SFBJV

Monthly aerial surveysMonthly aerial surveys1987 1987 -- 19901990

Accurso 1992

Monthly aerial surveys Monthly aerial surveys 20052005--20072007

North Bay salt ponds

0

5000

10000

15000

20000

25000

30000

1998 2000 2002 2004 2006 2008

BuffleheadCanvasbackRuddy DuckScaup

North Bay salt pondsNorth Bay salt ponds1999 1999 -- presentpresent

South Bay salt ponds South Bay salt ponds 2002 2002 -- presentpresent

South Bay salt ponds

0

500010000

1500020000

25000

3000035000

4000045000

50000

2001 2002 2003 2004 2005 2006 2007 2008 2009

BuffleheadCanvasbackRuddy DuckScaup

Research on diving ducks in Research on diving ducks in SFBJV RegionSFBJV Region

I. Foraging areasI. Foraging areasA. Habitat useA. Habitat useB. Response to changing habitats: salt pond conversionB. Response to changing habitats: salt pond conversion

II. Changing prey populationsII. Changing prey populationsA. Diet and response to A. Diet and response to invasivesinvasivesB. Carrying capacityB. Carrying capacity

III. Disturbance III. Disturbance A. Response to ferry trafficA. Response to ferry trafficB. Trail useB. Trail use

IV. ContaminantsIV. ContaminantsA. Effects on body conditionA. Effects on body conditionB. CrossB. Cross--seasonal effectsseasonal effects

V. Catastrophic eventsV. Catastrophic eventsA. Oil spill A. Oil spill -- CoscoCosco BusanBusan

Factors influencing intertidal and Factors influencing intertidal and subtidalsubtidalforaging habitatforaging habitat

Net Sediment DeclineMud flats decreasing at a rate of 14% per decade

Tidal wetland restorationSediment loss towetland accretion?Salt pond conversion

Climate change predicted loss of South and Central Bay mudflats due to sea level rise(Galbraith et al. 2002)

Eelgrass loss and current restorations

Diving duck foraging areasDiving duck foraging areas

0

10

20

30

40

50

60

DEC JAN FEB MAR

Hom

e R

ange

Siz

e (k

m2 )

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Med

ian

Dep

th (m

eter

s)

Nov Dec Jan Feb

Lesser ScaupGreater Scaup

Foraging depth preferences and Foraging depth preferences and available habitatavailable habitat

Lesser scaup -.5 to 1m, Greater scaup 0 to 1.5mAvailable foraging area at a 1.2m tide = 32%

of the Bay

Climate changeClimate change

How will foraging habitat change with:

Sea level riseFreshwater flowSediment change

Eelgrass prey densities and Eelgrass prey densities and waterfowl foraging behaviorwaterfowl foraging behavior

Behavior in Eelgrass

0%

25%

50%

75%

100%

AMCO BUFF FOTE HEGR RUDU SCAUP SUSC WCGR WEGU

species/group

obse

rved

beh

avio

r (%

)

PreenSwimRestForage

Pilot study in conjunction with RB Pilot study in conjunction with RB Audubon Audubon

Evaluate Evaluate waterbirdwaterbird foraging foraging behavior in relation to invertebrate behavior in relation to invertebrate and fish availabilityand fish availability

Sampling based on grid system with Sampling based on grid system with known eelgrass and nonknown eelgrass and non--eelgrass gridseelgrass grids

Future questions:Future questions:When do restored beds begin toWhen do restored beds begin to

approximate value of natural beds? approximate value of natural beds? What is the effect of herbivores onWhat is the effect of herbivores on

eelgrass health? (eelgrass health? (FersonFerson 2007)2007)

Response to end of salt production in Response to end of salt production in North Bay pondsNorth Bay ponds

05000

1000015000

2000025000

3000035000

1989 1991 1993 1995 1997 1999

Num

ber o

f Bird

s

0100020003000400050006000700080009000

1989 1991 1993 1995 1997 1999

Num

ber o

f Bird

s

C. Diving Benthivores

D. Canvasbacks

Benthivores crashed as water levels fell after salt-making ended. Estuary-wide surveys indicated emigration, not displacement.

(Takekawa et al. 2001)

North Bay salt ponds

0

5000

10000

15000

20000

25000

30000

1998 2000 2002 2004 2006 2008

BuffleheadCanvasbackRuddy DuckScaup

2007 breach

Canvasback movements Canvasback movements to the Delta and to the Delta and Sacramento ValleySacramento Valley

Mean winter abundance and distribution, 2005 -2007

Distribution of diving ducks in South Distribution of diving ducks in South Bay salt ponds during the winterBay salt ponds during the winter

Shoals projectShoals projectHow will mudflat habitat change as salt ponds are breached?

Measuring pre and post breach:Bathymetric changeInvertebrate community composition and densities Waterbird community compositionWaterbird foraging behavior and diet

CorbulaCorbula amurensisamurensis(overbite clam)

Euryhaline bivalve introduced to northern SFB ~1986Became dominant clam species in northern SF Bay

How important is Corbula in diving duck diets?

What is the prey value of Corbula compared to Macoma?

InvasivesInvasives: Waterfowl response to : Waterfowl response to changing prey specieschanging prey species

Nichols et al. 1990

Percent of diving ducks consuming dominant prey items

0

20

40

60

80

100

Amphipods Isopods M. balthica C.amurensis

Seeds Other

% o

f tot

al b

irds

CANVGRSCLESC

Diving duck winter diet Diving duck winter diet

Prey sizesPrey sizes

Scaup <12 mm

Canv 12-25 mm

0.000.010.01Other

0.110.000.00plant material

0.000.080.00clam siphons

0.000.080.00Synidotea

0.000.040.00Hemigrapsusoregonensis

0.000.040.08Musculistasenhousia

0.000.000.17Pyromaiatuberculata

0.890.710.00Corbulaamurensis

0.000.050.74Venerupisphilippinarum

92512NSuisun NorthCentral

Surf scoter diet differs among Surf scoter diet differs among subsub--bays bays

What is the role of herring roe in winter diet? Evaluating with isotopes

Macoma densities remained similar throughout winter at most transects

Corbula densities declined significantly over winter at each transect – Scaupforaging declined

0

40

80

120

160

0

200

400

600

800

Ca CC He MI SQ

fallspring

M. balthica

**

*

*

*

P. amurensis

*

springfall

Num

ber

m-2

Poulton, V. K., J. R. Lovvorn, and J. Y. Takekawa. 2002. Clam density and scaup feeding behavior in San Pablo Bay, California. Condor 104: 518-527.

Clam depletion across winter Clam depletion across winter

Prey ValueHandling time and gross energy intake (kJ/s)

(Richman and Lovvorn 2004)

Macoma Corbula

Prey / m20 1000 2000 3000 4000 5000

0.0

0.2

0.4

0.6

Prey /m20 1000 2000 3000 4000 5000

Gro

ss E

nerg

y (k

J/s)

0.0

0.2

0.4

0.6

Prey <6 mm long at 3 cm depthPrey 6-12 mm long at 3 cm depthPrey <6 mm long at 6 cm depth

Carrying capacityCarrying capacity

Recently funded through SF Foundation with SFBJV support

Collaborative effort with Jim Lovvorn, SIU

Individual-based modelsDaily Ration Models (Lovvorn and Baldwin 1996, Michot 1997)

Spatial Depletion Models (Gill et al. 2001, Goss-Custard et al.2003)

Carrying capacity:data available for modeling

Macroinvertebrate density and patchiness2000+ coresBDAT – online invertebrate datasets from several sampling efforts

Prey preference and handling times“Giving up” thresholds

Complications:Differentiating between fish and bird predatorsCapturing prey patchiness at several scales

Disturbance:Disturbance:Proposed increase in ferry numbers and Proposed increase in ferry numbers and

routesroutesConcern: Disturbance and displacement effectsObjectives:

1) conduct on-board ferry surveys to assess species-specific response distances2) examine waterbirdbehavior and abundance before and after watercraft in land-based surveys 3) document distribution of waterbirds along ferry routes with aerial surveys

Response to ferries differs by species Response to ferries differs by species

Western or Clark’s grebe

Scoter

Scaup

59 surveys on six existing ferry routes

Average response distance = 300 m

Total area of disturbance: behavioral response area (300 m) + variation in routes (200 m) = disturbance zone of 800 m

TakekawaTakekawa et al., in reviewet al., in review

Ferry routes and disturbance effects Ferry routes and disturbance effects

Applied buffers to existing and proposed routes

Existing ferry routes - total effect zone = 106km2or 11% of SFB and 3% of foraging zone

10 proposed ferry routes increase effect zone to 23% of SFB and 18% of foraging zone

Canvasback: 142.2 +/- 16.6 m

Scaup (lesser, greater combined): 132.3 +/-16.2 m

Ruddy Duck: 106.5 +/- 9.6 m

Bufflehead: 138.5 +/- 12.8 m

Trail use disturbance (mean +/Trail use disturbance (mean +/-- 1 SE)1 SE)

White and Trulio 2008

Minimizing impactsMinimizing impacts

Establish protected areas

Restricted winter use in important foraging areas

Contaminants in SFB waterfowlContaminants in SFB waterfowlAccumulated from benthic prey

Corbula represents increased risk 3x more Selenium than Macoma (Linville et al. 2002)

22x more Cadmium than Macoma (Wallace et al. 2003, Wallace and Luoma 2003)

Selenium and mercury elevated in scoters and scaupHuman consumption advisory TMDL regulations

Known effects of Se and Hg:Altered glutathione metabolism and oxidative stressBody condition Reproductive toxicity = most sensitive endpoint

Canvasback body condition:Canvasback body condition:protein vs. seleniumprotein vs. seleniumTakekawaTakekawa et al. 2002 et al. 2002

Scoter body condition and departureScoter body condition and departure

Poor condition can negatively influence:

survival migration departure and timingbreeding propensity reproductive success

y = -0.1243x + 227.75R2 = 0.1833

405060708090

100110120130140150

700 800 900 1000 1100 1200

Mass (g)

Win

teri

ng S

ite D

epar

ture

(O

rdin

al D

ate)

De La Cruz et al., submitted

Selenium concentrations higher in Selenium concentrations higher in migrating than breeding area femalesmigrating than breeding area females

16 May 0616 May 06All BaysAll Bays

0

510

15

2025

30

35

40

45

50

SFB Winter Haines Spring Yellowknife

[Se]

ppm

dry

wt

11--14 June 0614 June 06

0

5

10

15

20

25

30

YK June 1-4 YK June 12-14 YK June 4 SFB Markedbirds

[Se]

ppm

dry

wt

Liver

Egg

Selenium in egg and liverSelenium in egg and liver

Egg effect concentrationLiver effect concentration

Mean arrival breeding area arrival date = 25 MayMean arrival breeding area arrival date = 25 MayMean settling date = 27 May Mean settling date = 27 May

Post Post CoscoCosco--BusanBusan researchresearch

Survival and behavior of Survival and behavior of 3 treatment groups3 treatment groups

RehabilitatedSham rehabMark and release

Collaborative work: Collaborative work: USGS, UC Davis USGS, UC Davis –– OWCN, OWCN, HSU, CDFGHSU, CDFG-- OSPROSPRCDFG, OSPR

Preliminary Results: survival of 3 treatment Preliminary Results: survival of 3 treatment groups after groups after CoscoCosco--BusanBusan

TakekawaTakekawa, De La Cruz (USGS), , De La Cruz (USGS), ZiccardiZiccardi, Massey (OWCN), , Massey (OWCN), GolightlyGolightly (HSU), Henkel (OSPR), (HSU), Henkel (OSPR), unpublunpubl. data. data

Research directions for the SFBJVResearch directions for the SFBJV

Ecology of shoal habitats

Continued work on wetland restoration effects on divers

Foraging ecology of ruddy ducks and bufflehead

Effect of climate change on foraging resources

Effectiveness of protection zones for increasing available foraging habitat

Value of restored versus natural eelgrass beds to waterfowl